Thermoprinting devices

ABSTRACT

In a thermoprinting device the printing elements necessary for printing any one of the characters of a system of recording information are distributed among a plurality of rows which are successively activated for printing on the same area of a thermosensitive carrier. The printing elements may be in the form of rows of bar groups forming subdivisions of a bar mosaic. Alternatively, the printing elements may be in the form of rows of character printing elements of full character configuration, the number of rows corresponding to the total number of characters of the system. In the latter case high speed printing may be obtained by progressively printing from all the rows at a time.

United States Patent Henning Gunnar Carlsen Sandbjergvej. Sandbjerg, Osterskov 2950, Vedbaek. and

Erling Carlsen, Fuglevadsvej 2800 Kgs., L lgby, Denmark [72] lnventors [21] App]. No. 797,012

[22] Filed Feb. 6, 1969 [45] Patented Jan. 12, 1971 [32] Priority Feb. 8, 1968 [33] Denmark [54] THERMOPRINTING DEVICES 2 Claims, 14 Drawing Figs.

[52] US. Cl 219/216,

346/76 [51] Int. Cl 1105b 1/00 {50] Field ofSearch 219/201,

8/1960 Conrad Primary Examiner-R. F. Staubly Assistant ExaminerC. L. Albritton Attorney-Watson, Cole, Grindle & Watson ABSTRACT: In a thermoprinting device the printing elements necessary for printing any one of the characters of a system of recording information are distributed among a plurality of rows which are successively activated for printing on the same area of a thermosensitive carrier. The printing elements may be in the form of rows of bar groups forming subdivisions of a bar mosaic. Alternatively, the printing elements may be in the form of rows of character printing elements of full character configuration, the number of rows corresponding to the total number of characters of the system. In the latter case high speed printing may be obtained by progressively printing from all the rows at a time.

PATENTEB JAN 12 I97! sum 2 or 7 ATTORNEY PATENTIED'JANIZISYI' -sumsur7 ATTORNE PATENTED JAN-I. 21911 INVENTOR SHEET 5 OF 7 BY 7 Md/ L M w ATTORNEY PATENTEU Jmvzlsn 3.655241 SHEET 6 HF INVENTOR ,1 a (5 wh La [Many BY H I a n ATTORNEY PATENTE U JAN12|97| 5 sum 7' or 7 INVENFOR ATTORNEY TIIERMOPRINTING DEVICES BACKGROUND OF THE INVENTION This invention relates to a thermoprinting device, i.e. a device by means of which information can be printed on a thermosensitive record carrier, such as a sensitized sheet of paper, by means of selectively heated printing elements in heat transfer relationship with the carrier, a change of color being produced in the areas of the carrier to which heat is transferred from the printing elements. The printing elements consist of electric resistors to which current is supplied in accordance with signals received from a source of information, said signals being representative of information to be printed, usually in the form of letters, numerals, mathematical symbols, etc. The source of information may on principle be of any type, even mechanical, but the most logical use of thermoprinting devices is in combination with electronic equipment such as electronic computers or data processing equipment, thereby extending the principle of electronic operation to the printing unit and avoiding mechanical motion therein, except for the feeding of the record carrier, and also avoiding the use of printing ribbons or printing ink.

Thermoprinting devices are known, in which the printing elements are in the form of dots placed on a stationary support either in a single line for progressive printing or in a twodimensional pattern. In either case, it is impossible to print characters or symbols having a continuous contour, and if an attempt is made at improving the distinctness of the printed characters or symbols by increasing the fineness of the dot division, difficulties of both a mechanical and electrical nature are encountered.

It is the object of the invention to provide a thermoprinting device of the general type referred to which permits the printing of characters or symbols with a continuous or practically continuous contour.

SUMMARY OF THE INVENTION According to the invention, the printing elements are arranged in a plurality of rows, each row comprising in each of a plurality of positions printing elements contributory to the printing of all characters of a system of recording information, the printing elements in corresponding positions in all the rows in their totality being capable of printing the full outline of any one of the characters of said system, means being provided for successively presenting the same area of the record carrier to said rows, said signal receiving and current supplying means being arranged to supply signals to each of said rows of printing elements when this is in printing relationship with said area of the record carrier.

By placing the printing elements in a plurality of rows for successive printing as described, it becomes possible to use printing elements which would have overlapping or intersecting contours if placed in the same row so that the possibilities of truly representing characters or symbols having a continuous or practically continuous contour and/or characters or symbols of any desired configuration are greatly enhanced.

' According to one embodiment of the invention, the printing elements in each row are in the form of bar groups forming subdivisions of a bar mosaic suitable for selectively printing any one of a number of characters forming a system of recording information, the bar groups in corresponding positions in the various rows combining to form a complete bar mosaic. A bar mosaic is a figure consisting of a number of bars which in their different combinations may represent any one of the characters of a system of recording information. It will be realized that if printing elements in the form of a bar mosaic are placed in a single row, there must of necessity be gaps between the various bars. By placing bar groups of a bar mosaic in a plurality of rows as described, the bars of the various groups may have overlapping configurations so that it becomes possible to avoid some of the gaps or all of them. A very considerable improvement is obtained already by placing bar groups in two rows.

According to another embodiment of the invention, the printing elements are in the form of character printing elements of full character configuration, the character printing elements in corresponding positions in all the rows combining to form a full selection of the characters of said system of recording information. In this case the configuration of the printed characters can be selected as desired, because the printing takes place in each position of the printed line from a selected one of the full character printing elements present in the position considered in all the rows. This embodiment is particularly suitable for the continuous printing of infonnation from a source from which a multitude of lines to be printed are available in rapid succession, as will be explained below.

According to a third embodiment of the invention, the distribution of the printing elements on a plurality of rows may be combined with distribution of the printing elements between various superposed layers, which forms the subject of an application filed by the same applicants on the same day.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show examples of bar mosaics,

FIG. 3 shows a diagram illustrating the basic principle of operation of a thermoprinting device in which the printing elements are arranged in the form of bar mosaics,

FIG. 4 is an enlarged perspective view of a thermoprinting block according to one embodiment of the invention,

FIG. 5 shows a fraction of the surface of the printing block of FIG. 3 on a still larger scale, the fraction being indicated by the reference V on FIG. 3,

FIG. 6 is a block diagram showing an example of the electronic equipment of a thermoprinting device according to the invention,

FIGS. 7 and 8 are diagrammatic illustrations of examples of the paper feed of a thermoprinting device according to the invention,

FIG. 9 is a fractional perspective view of a printing member according to another embodiment of the invention,

FIG. 10 is a block diagram showing an example of the electronic equipment of a thermoprinting device having a printing member according to FIG. 9,

FIG. 11 is a diagram illustrating progressive printing on a sheet of thermosensitive paper by means of a printing member according to FIG. 9,

FIG. 12 is a diagrammatic side view of the structural arrangement of a thermoprinting device for effecting progressive printing,

FIG. 13 is a perspective view on an enlarged scale of a structural element of the thermoprinting device of FIG. 12, and

FIG. 14 is a fractional perspective view of a printing member according to a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a bar mosaic comprising seven bars and the manner in which the numerals of the decimal system can be formed from different combinations of the bars of the mosaic. FIG. 2 shows a bar mosaic comprising 16 bars from which, in addition to the numerals, also the letters of the Latin alphabet can be formed.

FIG. 3 shows how printing elements in the form of electric resistors l7 arranged in accordance with the pattern of FIG. 1 are connected through contacts Kl-I(7 to a battery. If e.g. the contacts K2, K5 and K7 are closed, the printing elements 2, 5 and 7 are heated. These are the elements corresponding to the numeral 7 as represented in FIG. 1. If now a piece of thermosensitive paper is pressed against the bar mosaics, the numeral 7 is printed on the paper by contact copying. The contacts Kl--K7 represent electronic contacts which are controlled from the store of an electronic computer, such as will be described in more detail below.

In FIGS. 4 and 5, I0 is an electrically insulating flat member forming a substrate, on which a number of bar groups of bar mosaics are placed side by side in two rows, the arrangement being such that the bar groups in corresponding positions in the two rows would combine to form a complete bar mosaic if placed on top of one another. In this embodiment the bar mosaics are supplemented by two additional bars 8 and 9 and a bar representing a decimal point or comma.

Alternatively the bar mosaics could be subdivided into a greater number of groups arranged in a corresponding number of rows. Owing to the subdivision of the bar mosaics these may be so arranged that if placed on top of one another they would overlap at some of or all of their junctions, thereby to eliminate or reduce the gaps occuring in characters printed from the bar mosaic.

The bars constitute printing elements of the thermoprinting device and are selectively activated for printing by the supply of current through supply conductors 11. Printing from the bars 2, 3, 4, 6, 8 in the first row is effected with the thermosensitive paper in one positions, whereupon the paper is fed forward to a new position in which the printing is then effected from the bars 1, 5, 7, 9, 0 in the second row. Both the bars and the supply conductors consist of film deposits on the surface of the insulating member 10. The insulating member 10 is mounted on a body 12 consisting of material of high heat conductivity, the body 12 serving both as a support for the insulating body and as a heat sink for absorbing excess heat from the insulating member, and thereby, from the printing elements, and dissipating this heat to the environment. To increase the heat dissipating surface of the body 12, ribs 13 are provided.

The substrate member 10 may e.g. consist of fused quartz (silica) or boron silicate glass. It should be thin enough to permit rapid transfer of excess heat from the printing elements to the heat sink, but on the other hand thick enough not to permit excessive travel of heat from the printing elements during printing. A thickness of 0.5 mm. has been found suitable for the conditions of operation of a printing device for a desk calculator.

The film deposit constituting the printing elements 1-8 may be applied to the substrate 10 by well known circuit printing methods such as thin film technique, thick film technique or planar technique. Suitable examples are evaporation (condensation from the vapor phase) and sputtering (cathode atomization). Application by dotation or diffusion in combination with epitaxial processing is also possible and material applied in this way is intended to be comprised under the term film deposit.

As an example, the printing elements may consist of Cr in a thickness corresponding to gran/[1 (about 300 Angstrom 0.00003 mm.) applied bysptit'tering and having a length of 1 mm. and widths of 0.1-0.2 mm, while the supply conductors may consist of Au in a thickness corresponding to 0.59/1] 1, (about 5000 Angstrom 0.0005 mm.) and martian ofO.l-0.2 mm.

To protect the printing elements and supply conductors against mechanical and chemical influences, the printing surface of the member 10 may be covered with an electrically insulating wear resistant and chemically protecting film. As an example, such a film may consist of quartz which is applied in a thickness of 5000-10000 Angstrom by radio frequency sputtering.

Typical values of the currents and voltages used for the pulses for activating the printing elements are 27 Volt and 30 mA. A suitable heating time for printing elements consisting of a Cr film as above described is msec., whereby the average temperature will be raised to about 160 (3., which is suitable for printing on thermosensitive paper available in the trade. The heating time may be shorter, e.g. as low as 5 msec. or even lower in the case of other materials and dimensions. The heating time may also be selected longer where longer printing times are permissible e.g. in the case of manually operated computers. The heating time, i.e. the duration of the current pulses, constitutes the elementary printing time. The total printing time depends on the system selected for the activation of the printing elements. Some examples of such systems will be described below.

The heat sink 12 may consist of aluminum and should be so dimensioned that the heat sink will maintain the surface of the substrate on a low average temperature and limit the mutual heating of adjacent printing elements by removing excess heat as rapidly as possible. For a table computer a heat sink having a thermal resistance of l0 C./Watt has been found suitable.

An example of electronic equipment for use with the printing member described is illustrated in FIG. 6. l4 is the storeof a computer, from which information is to be printed,-and i5 is the corresponding decimal point store-The resistors 2, 3, d, 6, 8 represent the bars in the various positions of the first row, while the resistors l, 5, 7, 9, 0 represent t'he'bars in the various positions of the second row. 16 is a dec'oderp'by. means of which a line of characters in the computerzstore andany decimal points are transferred to two printing stores 17.1 and 17.2 in first row bar mosaic language, and second row bar mosaic language respectively. 18 is a supply line for clock pulses. 19 is a row selector, by means of which first one and then the other row of bar groups is selected for printing by means of current pulses from a printing pulse generator 20. 51 is a paper feed switch, by means of which the paper feed of the printing device is stepped forward between printing from the first row and printing from the second row. The arrangement is such that the next paper feeding step is released only when printing from the first row has been effected in the next line to be printed. in other words upon printing of a line the thermosensitive paper remains stationary until printing of the next line has already been halfway done. The line 21 symbolizes the timing that must exist between the printing pulses and the clock pulses so that the transmission of printing pulses is initiated when a whole line of characters has been transferred from the computer store to the printing store. The stores 17.1 and 172 may be replaced by a single store which is usedfirst for the first row and then, upon feeding of the paper, for the second row.

With the electronic equipment illustrated in FIG. 6 all bar groups in a row are activated simultaneously. Thus with the values mentioned above the total printing time will be 40 msec. the paper feeding time. However, the delay resulting from the paper feed may in fact be disregarded because there is only one paper feeding movement per printed line, just as if printing had been made from a row of complete bar mosaics. The only difference is that the print occurs on the thermosensitive paper a little later than it would have done with complete bar mosaics in one row, but when a succession of lines are printed the total printing time for all the lines will not be prolonged.

Where the printing speed is not of the essence, the bars of each row may be activated for printing successively rather than all at a time, i.e. by combining the diagram with that of FIG. 6 of an application filed by the same applicants on the same date. The printing stores will then be considerably smaller. Preferably bars in the same position in all characters to be printed in a line, where such bars occur, are then picked for simultaneous printing, and this operation is repeated for bars in other positions until bars in all positions have been picked for printing. If the bars are picked in a jumping succession, the danger of mutual thermal influence between adjacent printing elements is reduced. Since the time consumed by the electronic operations can be regarded as negligible, the total printing time would then be eight times the printing time for one bar, but on the other hand the printing stores would be reduced to one-eight. Thus assuming this time to be 20 msec., the total printing time would be msec. This will be satisfactory for a desk calculator where ample printing time is available. The total printing time could be reduced by one-half if two bars were picked for printing at a time. However, in this case the printing stores must be double the capacity of those necessary for printing one bar at a time, but they would still require smaller capacity than those necessary in FIG. 6.

it will thus be realized that in selecting the system of activating the bars, printing speed has to be weighed against expense. Other systems than those described are also possible. E.g. the bar groups of a line may be printed one by one.

FIG. 7 shows how a thermosensitive paper sheet 22 is fed forward between the printing block 10, 12 of FIG. 4 and a sup port 23 so that heat may be transferred from the heated printing elements to the sheet by thermal'contact copying.

In the embodiment illustrated in FIG. 8, the paper sheet is fed forward between a glass plate 24, facing the position of an operator, and the printing block l0, 12, which is in this case arranged for inverted printing. The thermosensitive paper used in this case is of a type having a thermosensitive coating on the rear side, which causes a change of color on the front side of the paper. Thus, in the embodiment of FIG. 8 the printed characters become directly visible immediately upon completion of printing.

In the embodiment illustrated in FIG. 9, the printing elements are in the form of full characters 42, which are arranged in a number of rows. Thus, in the example shown a set of s is arranged in a first row on the printing element 10, a set of 1's in a second row, etc. up to a set of 9s in a I0 row and a set of decimal points in an II row (not shown). In each position of the rows taken as a whole, or in other words in each column, all the characters 0-9 and the decimal point will be represented.

When using the printing member of FIG. 9, the paper must be fed eleven steps forward to print a'line. However, where a multitude of lines have to be printed in rapid succession the delay resulting from this form of printing may be practically eliminated by printing the lines progressively as will now be explained with reference to FIGS. 10 and 11.

In FIG. 10, 52.0-52.. are 11 buffer stores each capable of storing a line to be printed. 53.053.. are decoders and 54.0- -54.. printing stores for the respective rows of character printing elements of the printing member of FIG. 9. The resistors 42 represent the character printing elements 42. 55 is a printing pulse generator and 56 apaper feed switch. The short vertical arrows represent clock pulse inlets. A signal representing a line of characters to be printed is stored in the buffer store 52.0 and remains there until the next line signal arrives. It is then transferred to the buffer store 521 and at the same time decoded into the O-row printing store 54.0 for the printing of any Os occurring in the line, while the new line is stored in the buffer store 52.0. Similarly, when a third line signal arrives, the first line signal is transferred to the buffer store 52.2 and at the same time decoded into the l-row printing store 54.], and the second line signal is transferred to the buffer store 52.] and decoded into the printing store 54.0, while the third line is stored in the buffer store 52.0 etc. After each printing by means of a printing pulse from the generator 55 the thermosensitive sheet is fed a step forward corresponding to the spacing of the rows of printing elements 42, which is selected in accordance with the desired line spacing of the record sheet.

The manner in which characters are printed progressively on a thermosensitive sheet is illustrated in FIG. 11.

It is assumed that the following FIGS. are to be printed in I2 successive lines:

line No. 1: 0317 line No. 2: 2840 line No. 3: 0352 line No.4: blank line No. 5: blank line No. 6: 0123 line No. 7: blank line No. 8: 2222 line No 9: blank line No. 10: blank line No. 11: 5316 line No. 12: 3904.

In a first position of the sheet, a first line of this is in register with the row of Us of the printing member of FIG. 9, and since the FIG. to be printed comprises an 0 in the first position, the O in that position in the row of Us of the printing member is activated to print an O on the sheet. The sheet is now fed one line spacing forward so that the first line of the sheet comes into register with the row of Is of the printing member. Since the FIG. to be printed comprises a l in the third position, the l in that position in the row of ls of the printing member is activated to print a l on the sheet. In the same position of the sheet the second line thereof is in register with the line of 0s and since the second FIG. to be printed comprises an O in the fourth position, the O in that position in the row of Us of the printing member is activated to print an O on the sheet.

In this manner printing is continued progressively as long as the printing device receives signals representative of lines to be printed. It will be understood that when the sheet arrives in position for the printing of the I2 line, the first line is finished and comes out of the printing device. Thus, the printing of this line has taken a time corresponding to 12 steps of the paper feed. However, the second line follows after a time interval corresponding to only one step of the paper feed and the same applies to all subsequent lines so that when a multitude of lines are to be printed in rapid succession, the initial delay will be of no consequence. When there are no more lines to be printed, the device is arranged to continue printing blank lines, in a number sufficient for completing printing of the last line and feeding it out of the device.

FIGS. 12 and 13 illustrate diagrammatically the mechanical arrangement of a thermoprinting device for the progressive printing of lines in the manner described. The device comprises a plurality of printing members 10 corresponding to the various rows of the printing member of FIG. 9. The printing elements on the printing surface 25 are not shown. The printing members are arranged along the circumference of a circle and each is provided with a radial extension 26, in. which a supply conductor 27. for each printing element is printed with a covering insulating layer 28. A perforated feeding cylinder 29 is mounted for rotation coaxially with the printing surfaces of the printing members with its surface in close proximity thereto. Inside the cylinder 29 there is mounted a stationary pneumatic distributor 30, which has an arcuate chamber 31 extending in close proximity to the perforated wall of the cylinder 29. The outer wall of the chamber 31 is perforated. A sheet 22 of thermosensitive paper is fed forward between two continuously rotating rollers 32 and 33, the speed of which is governed by a loop indicator diagrammatically represented at 34. The pneumatic distributor 30 is connected to a source of alternate air pressure and suction. In the periods where the pressure .is above that of the atmosphere, air is blown out through the perforations of the chamber 31 and the perforated wall of the cylinder 29 to press the sheet 22 firmly against the printing surfaces of the printing members 10 where the sheet remains stationary while printing of characters in selected positions takes place simultaneously from all the rows by means of electronic equipment corresponding to that of FIG. 10. The pneumatic source is then switched over to suction, whereby the sheet 22 is applied firmly to the perforated surface of the cylinder 29 so as to be fed one step forward by the latter.

Cooling of the printing members may be effected in any suitable manner. Thus the spaces between the radial exten' sions of the printing elements may be closed by means of circumferentially extending partitions such as illustrated at 35 to form chambers 36 for the circulation of a cooling medium.

The printing device of FIG. 12 may be constructed for a larger number of printing members, e.g. 64, by increasing the diameter of the cylinder 29 and/or by mounting printing members along a greater part of the circumference of the cylinder, whereby it becomes possible to print all the characters of the alphanumeric system.

The number of rows of printing elements necessary for covering a system of characters may be reduced by arranging the printing elements in pairs of superposed rows with insulating layers therebetween as illustrated in FIG. 14, thereby combining the present invention with that covered by application Ser. No. 796,955 filed by the same applicants on the same day as this application. A further reduction can be obtained by superposing printing elements in a greater number of layers, e. g. 4, 8, 16 or 32 in the case of the alphanumeric system.

We claim:

1. A thermoprinting device comprising a system of printing elements in the form of electric resistors, means for maintaining a thermosensitive record carrier in cooperative relationship with said resistors, and means for receiving signals representative of information to be printed and for selectively activating said printing elements by supplying current thereto in accordance with the signals thus received, characterized in that said printing elements are in the form of a plurality of rows of bar groups, each bar group being a subdivision of a complete bar mosaic, the bar groups in corresponding positions in all the rows combining to form a complete bar mosaic, means being provided for feeding said record carrier forward in steps equal to the spacing of said rows, thereby successively presenting the same area of the record carrier to said rows, said signal receiving and current supplying means supplying signals to each of said rows of printing elements when said rows are in printing relationship with said area of the record carrier. 7

2. A thermoprinting device as in claim '1, in which there are a first and a second row of bar groups placed at a spacing corresponding to the desired line spacing of the record, means being provided for keeping the record carrier in printing relationship with both rows of bar groups at a time and for feeding the record carrier forward relative to'lthe 'rows of bar groups in such a manner that upon activation of the first row of bar groups by means of a first signal representative of a first line of characters to be printed the record carrier is relatively advanced through a distance corresponding to the desired line spacing of the record and then remains stationary until the second row of bar groups has been activated by means of said first signal and said first row of bar groups has been activated by means of said first signal and said first row of bar groups has been activated by means of a second signal representative of the next following line of characters to be printed. 

1. A thermoprinting device comprising a system of printing elements in the form of electric resistors, means for maintaining a thermosensitive record carrier in cooperative relationship with said resistors, and means for receiving signals representative of information to be printed and for selectively activating said printing elements by supplying current thereto in accordance with the signals thus received, characterized in that said printing elements are in the form of a plurality of rows of bar groups, each bar group being a subdivision of a complete bar mosaic, the bar groups in corresponding positions in all the rows combining to form a complete bar mosaic, means being provided for feeding said record carrier forward in steps equal to the spacing of said rows, thereby successively presenting the same area of the record carrier to said rows, said signal receiving and current supplying means supplying signals to each of said rows of printing elements when said rows are in printing relationship with said area of the record carrier.
 2. A thermoprinting device as in claim 1, in which there are a first and a second row of bar groups placed at a spacing corresponding to the desired line spacing of the record, means being provided for keeping the reCord carrier in printing relationship with both rows of bar groups at a time and for feeding the record carrier forward relative to the rows of bar groups in such a manner that upon activation of the first row of bar groups by means of a first signal representative of a first line of characters to be printed the record carrier is relatively advanced through a distance corresponding to the desired line spacing of the record and then remains stationary until the second row of bar groups has been activated by means of said first signal and said first row of bar groups has been activated by means of said first signal and said first row of bar groups has been activated by means of a second signal representative of the next following line of characters to be printed. 